Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

Methods and apparatus for dermatology treatment are provided which
involve the use of continuous wave (CW) radiation, preheating of the
treatment volume, precooling, cooling during treatment and post-treatment
cooling of the epidermis above the treatment volume, various beam
focusing techniques to reduce scattering and/or other techniques for
reducing the cost and/or increasing the efficacy of optical radiation for
use in hair removal and other dermatological treatments. A number of
embodiments are included for achieving the various objectives indicated
above.

Claims:

1. A photocosmetic device comprising: a head adapted for applying
radiation to skin, the head comprising an output aperture and a scanner
configured to scan radiation over the output aperture as the head is
moved over the skin, a motion sensor coupled to the head and adapted to
generate one or more signals indicative of a rate of movement of the head
as it is moved over the skin, and controls coupled to the head for
receiving said one or more signals and for controlling the rate of
scanning in response to said one or more signals.

2. The photocosmetic device of claim 1, wherein the device further
comprises an alert mechanism configured to provide an alert to an
operator regarding the rate of head movement over the skin.

3. The photocosmetic device of claim 2, wherein the alert mechanism is
further configured to alert the operator of said device if the determined
rate of movement is outside of a particular range of rates.

4. The photocosmetic device of claim 3, wherein the alert mechanism
comprises at least one of an audio output device, a visual output device,
and a tactile output device.

5. The photocosmetic device of claim 1, wherein the motion sensor further
comprises a mechanism configured to determine the rate of movement of the
head over the skin.

6. The photocosmetic device of claim 5, wherein the mechanism is further
configured to determine if the head is moving at a rate within a
predetermined range of rates, and to provide a further signal to the
controls based on said determination of the rate of movement.

7. The photocosmetic device of claim 1, wherein the controls adjust the
output of the device if the rate is outside a predetermined range of
rates.

8. The photocosmetic device of claim 1, wherein the controls are
configured to terminate application of the radiation if the rate is
outside a predetermined range of rates.

9. The photocosmetic device of claim 1, wherein the motion sensor is
selected from the group of a kinematic motion sensor, an optical motion
sensor, an electrical motion sensor, a thermal motion sensor, and a
magnetic motion sensor.

10. The photocosmetic device of claim 1, wherein the head is configured
to apply continuous wave radiation.

12. The photocosmetic device of claim 1, wherein the head comprises a
skin contacting surface and the scanner scans radiation over the skin
contacting surface.

Description:

RELATED APPLICATIONS

[0001] The present application is a continuation of U.S. application Ser.
No. 11/437,434, filed May 19, 2006, entitled "Heads for Dermatology
Treatment," which is a continuation of U.S. application Ser. No.
10/274,582, filed Oct. 21, 2002, now issued as U.S. Pat. No. 7,077,840,
entitled "Heads for Dermatology Treatment," which is a continuation of
U.S. application Ser. No. 09/634,981, filed Aug. 9, 2000, now issued as
U.S. Pat. No. 6,511,475, entitled "Heads for Dermatology Treatment,"
which is a continuation of U.S. application Ser. No. 09/078,055, filed
May 13, 1998, now issued as U.S. Pat. No. 6,273,884, entitled "Method and
Apparatus for Dermatology Treatment," which claims the benefit of U.S.
Provisional Application Nos. 60/046,542 filed May 15, 1997 and 60/077,726
filed Mar. 12, 1998. The entire contents of all above-listed applications
are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

[0002] This invention relates to apparatus for using optical radiation to
treat dermatological problems and, more particularly, to heads for such
apparatus which heads provide an elongated focus area at a selected depth
and/or selected preconditioning, for example heating and/or cooling, of a
treatment area.

BACKGROUND OF THE INVENTION

[0003] Lasers, lamps, and other sources of electromagnetic radiation,
particularly in the optical wavebands, are being increasingly utilized
for various dermatological treatments and, in particular, for the removal
of unwanted hair, spider veins, leg veins, other veins or other blood
vessels which are visible through the patient's skin, lesions, port-wine
stains, tattoos, and the like. In performing such treatments, it is
desirable that the cost for the treatment be kept as low as possible,
consistent with achieving desired results, and that risk of injury to the
patient be minimized.

[0004] Since continuous wave (CW) lasers and other CW radiation sources
are typically substantially less expensive than pulsed sources of
comparable wavelength and energy, for cost reasons, it would be
preferable to use CW sources rather than pulsed sources for such
dermatological treatments. However, in order to avoid injury to the
patient, the duration of energy application to a given area of the
patient's skin must be controlled, this generally resulting in the more
expensive pulsed light sources being used for the various dermatological
treatments. Further, since the only way to get radiation to areas where
treatment is desired, which areas are normally in the dermis, is to
transmit the radiation to such area through the overlying epidermis, some
portion of incident radiation is absorbed in the epidermis creating the
potential for damage thereto. This is a particular problem where melanin
is being targeted in the dermis, as is for example the case for various
hair removal treatments, since there is a substantial concentration of
melanin in the lower portion of the epidermis at the dermal/epidermal
(DE) junction. Further, the deeper in the dermis that treatment is
desired, and/or the larger the element being treated, the more energy
must be used, this generally involving the use of a more powerful laser
or other radiation source and/or operating such source for longer time
durations. This further increases the potential for epidermal damage.

[0005] Some attempts have been made in the past to scan a CW radiation
source, such as the laser, over a treatment area, which has been done
with the radiation source spaced from the skin in order to facilitate
movement of the source. However, techniques currently utilized for
protecting the epidermis frequently involve contact cooling of the
epidermis and, for certain treatments such as hair removal, performing
the treatment with pressure applied to the patient's skin is also
desirable. Irradiation by use of a head in contact with the skin also
permits more efficient transfer of energy into the patient's skin,
thereby reducing the size of the source required for a given treatment
energy density and, therefore, reducing the cost of such source. This
cost could be further reduced if the radiation source is not the only
source being utilized to heat the area under treatment.

[0006] Another problem in performing laser dermatology treatments,
particularly when such treatment is to be performed over an area larger
than the optical aperture of the applicator being utilized, is to obtain
substantially uniform irradiation over the area so that sufficient
radiation is applied to all portions of the area to achieve the desired
treatment, while no portion of the area has so much radiation applied
thereto as to cause thermal damage to the skin. Such uniform irradiation
is very difficult with a pulsed source which typically utilize a circular
aperture. Typically, the procedure followed is to irradiate a spot with a
given pulse and to then reposition the head to an adjacent spot for
irradiation. If the spots do not overlap, there will be portions of the
area under treatment which do not receive radiation and, unfortunately,
the radiation output is frequently not uniform over the entire optical
aperture, being greater near the center, and less at the edges.
Therefore, there is generally some overlap between adjacent spots.
However, this results in some portions of the area under treatment
receiving at least a double dose of radiation, which poses a potential
danger of thermal damage in these overlap areas. Substantially uniform
irradiation of a treatment area is therefore virtually impossible with a
pulsed radiation source utilizing existing techniques.

[0007] Another problem which increases the energy required from the
radiation source utilized is that, for existing systems, heating of the
target to achieve the desired therapeutic effect is accomplished solely
by radiation from the radiation source. If the temperature of the target
could be increased by some type of preheating of the target volume, the
amount of energy required from the radiation source to complete the job
would be substantially reduced. However, such preheating must be achieved
in a way such that the cost of such preheating is not greater than the
savings achieved by reduced requirements on the radiation source.

[0008] Similarly, in order to protect the epidermis, many procedures
require that the epidermis be cooled, preferably to the DE junction, to
at least a selected temperature, for example 10° C., 0° C.,
or even slightly lower, before radiation is applied. If contact cooling
starts when the head is over the target area, this means that there is
some delay, perhaps half a second to a second, between the time the head
is applied to the patient's skin and the time the radiation source is
fired. With CW, such a delay once the radiation source is over the target
area is difficult to achieve and it is therefore preferable that
precooling of the epidermis occur for the target area before the
radiation source is thereover. An ideal procedure would be to preheat the
skin down to the target depth and then to precool to the DE junction,
leaving the target depth preheated. Mechanisms in general, and heads in
particular, for achieving such precooling and/or preheating followed by
precooling have not heretofore existed.

[0009] It is also desirable to be able to focus the optical radiation at
substantially the target depth. While heads have heretofore existed which
are capable of achieving such a focus on a given spot, faster operation,
particularly when operating in CW mode, although also when operating in
pulse mode under some circumstances, can be achieved if there is a line
focus at the target depth rather than a point focus. Mechanisms for
achieving such a line focus have also not heretofore existed.

[0010] A need therefore exists for improved apparatus for utilizing
optical radiation to treat various dermatological conditions, and in
particular, improved heads for use in such apparatus which facilitate
preheating and/or precooling of the target area, particularly when
operating in CW mode, but also when operating in other modes, and which
also facilitate achieving of a line focus for the radiation at a selected
target depth for enhanced, and in particular, more rapid treatment.

SUMMARY OF THE INVENTION

[0011] In accordance with the above, this invention provides various heads
for use in apparatus for effecting a selected dermatologic treatment in
an area of a patient's skin. For some embodiments, the head includes a
block formed of a material having good thermal transfer properties, a
plurality of first optical waveguide elements and a plurality of second
optical waveguide elements extending through the block, the first and
second optical waveguide elements being angled at first and second angles
respectively, which angles are selected so that light passing through the
first and second optical waveguide elements converge at a selected depth.
The optical waveguide elements have radiation applied thereto which is
appropriate for the selected dermatologic treatment. The selected depth
is in the area under treatment at which the dermatologic treatment is to
occur. For some embodiments, a recess is formed in a surface of the head
in contact with the patient's skin, the recess being at the distal end of
the optical waveguide elements, and the selected depth is at a selected
location in the recess. For these embodiments, a means is provided for
moving skin in the area under treatment into said recess as said recess
passes thereover. This means may, for example, include a source of
negative pressure connected to the recess. For preferred embodiments, the
block also has a skin contacting surface which retroreflects radiation
leaving the patient's skin. A mechanism may also be provided for
controlling the temperature of either the entire block or selected
portions thereof.

[0012] For other embodiments, the head includes an astigmatic lens having
an elongated outer surface, one side of said surface contacting the
patient's skin in the area to be treated along an elongated line. A
mechanism is provided which delivers light of a wavelength suitable for
the dermatologic procedure to the lens on a side thereof other than the
side contacting the patient's skin, the lens focusing light delivered
thereto to a selected depth in the patient's skin. The lens may be a
cylindrical lens with a diameter such that light delivered thereto is
focused to the selected depth, and may be mounted to be either stationary
or rotating as the head is moved over a treatment area. For some
embodiments, the lens is treated so as to normally have total internal
reflection, the total internal reflection being broken at a surface of
the lens in contact with the patient's skin. To achieve the desired
focus, the radius of curvature of the cylindrical lens for some
embodiments is less than or equal 10 mm. For some embodiments, the
selected depth is that for a portion of a hair follicle responsible at
least in part for hair growth, for example, the hair bulge or the hair
bulb. The selected depth may, for example, be 1 mm to 5 mm.

[0013] The mechanism for delivering light to the lens may deliver light
along a line substantially parallel to the elongated line contacting the
patient's skin surface and/or may cause light to be delivered to the lens
at a variety of angles. A cooling mechanism may also be available for the
patient's skin before the lens makes contact with the skin and/or while
the lens is in such contact, the cooling mechanism for some embodiments,
including a mechanism for cooling the lens. For some embodiments, the
lens focuses light at said selected depth to an astigmatic focus area
having a long dimension substantially parallel to the elongated line of
lens contact with the skin. Finally, for some embodiments, the mechanism
delivering light to the lens scans along the lens in its elongated
direction, the scanning being at a selected rate.

[0014] More generally, the invention includes a focusing element having a
light receiving region, a light delivery region which is adapted to be in
contact with the patient's skin and a region which focuses light entering
at said receiving region, the focus, when such element is in contact with
the patient's skin being to an elongated astigmatic focus area at a
selected skin depth. A mechanism is included which delivers light of a
wavelength suitable for the dermatologic procedure to the light receiving
region. The selected depth for some embodiments is the depth for a
portion of a hair follicle responsible at least in part for hair growth,
for example the hair bulge and/or hair bulb, and may be approximately 1
mm to 5 mm into the skin. A cooling mechanism for the patient's skin may
also be provided, which mechanism is operated before the element makes
contact with the skin and/or while the element is in contact therewith.

[0015] In accordance with still another embodiment of the invention, the
head includes an optically transparent channel for delivering optical
radiation of a wavelength appropriate for effecting the treatment in the
area, a head portion of a thermally conductive material mounted relative
to the channel so that it moves over each segment to be treated of such
area before the channel, and a thermal component which controls the
temperature of the head portion, and thus of each skin segment prior to
treatment. In particular, the component may cool the portion, and thus
each skin segment prior to treatment and/or the component may heat the
portion, and thus heat each segment prior to treatment. The head may
include a block formed of a material having good heat transfer
properties, the block being adapted to move over the area during
treatment, the channel being formed through the block and the portion
being a portion of the block which is forward of the channel as the block
is moved over the area. The head portion forward of the channel may be
divided into a first thermally conductive portion which is heated and a
second thermally conductive portion which is cooled, which portions are
thermally insulated from each other, the first portion heating the
patient's skin to the depth where treatment is to be performed and the
second portion then cooling the patient's epidermis prior to irradiation.
The head may also include a portion of a thermally conductive material
mounted relative to the channel so that it moves over each segment to be
treated of the area after the channel; and a thermal component which
cools such rear head portion, and thus each skin segment after treatment.

[0016] While for preferred embodiments, preheating of the skin in the
treatment area is accomplished in conjunction with the use of CW
radiation and movement of the head over the treatment area, this is not a
limitation on the invention, and preheating of the treatment area is also
advantageous when employed with a pulsed radiation source. For such
applications, preheating could be achieved by heating the waveguide or
the portion of the head in contact with the segment under treatment prior
to treatment to heat the skin down to at least to the depth where
treatment is desired to a temperature which temperature is below that at
which thermal damage occurs; and to then cool the surface in contact with
the epidermis to cool the epidermis before irradiation begins. This
results in the area under treatment having an elevated temperature when
irradiation begins, thereby reducing the energy required from the
radiation source. Alternatively, a low energy radiation source, which can
be either the same or different than that used for treatment, can be used
to perform the preheating operation.

[0017] The foregoing and other objects, features and advantages of the
invention will be apparent in the following more particular description
of preferred embodiments of the invention as illustrated in the
accompanying drawings.

IN THE DRAWINGS

[0018] FIG. 1 is a semi-schematic perspective view of apparatus suitable
for practicing the teachings of this invention;

[0019]FIG. 2 is a sectional view of a head useful for practicing the
teachings of this invention in accordance with a first embodiment;

[0020]FIG. 3 is a sectional view of a head suitable for practicing the
teachings of this invention in accordance with a second embodiment;

[0021] FIG. 4 is a sectional view of a head suitable for practicing the
teachings of this invention in accordance with a third embodiment;

[0022] FIG. 5 is a perspective sectional view of a head suitable for
practicing the teachings of this invention in accordance with a fourth
embodiment;

[0023] FIGS. 6a-6b illustrate two embodiments of astigmatic transparent
channel suitable for use in a head of the various embodiments to deliver
radiant energy;

[0024]FIG. 7 is a side view of a head in use which is suitable for
practicing the teachings of this invention in accordance with a fifth
embodiment;

[0025]FIG. 8 is a side sectional view of a head suitable for practicing
the teachings of this invention in accordance with a sixth embodiment;

[0026]FIG. 9 is a top perspective view of a head suitable for practicing
the teachings of this invention in accordance with a seventh embodiment;

[0027] FIGS. 10a and 10b are a side sectional view and a front view,
respectively, of a head suitable for practicing the teachings of this
invention in accordance with an eighth embodiment;

[0028] FIGS. 11a, 11b and 11c are a side view, a front view when not in
contact with a patient's skin, and a front view in contact with the
patient's skin, for a head suitable for practicing the teachings of this
invention in accordance with a ninth embodiment;

[0029] FIGS. 12a and 12b are perspective views of portions of a head
illustrating various techniques for scanning a radiation source across an
astigmatic radiation delivery channel;

[0030]FIG. 13 is a side sectional view of a head suitable for practicing
one aspect of the invention in accordance with a tenth embodiment;

[0031]FIG. 14 is a graph illustrating the relationship between
temperature at the basal layer and scanning velocity when practicing the
teachings of this invention; and

[0032] FIG. 15 is a chart illustrating the relationship between scanning
velocity of the head and the maximum temperature of a hair bulb located
at a selected depth.

[0033] FIG. 16 is a chart illustrating the relationship between power per
unit length and maximum temperature of the hair bulb at a selected depth
for two different sizes of hair bulb.

DETAILED DESCRIPTION

[0034] FIG. 1 illustrates a general system suitable for practicing the
teachings of this invention. In FIG. 1, an area 10 of a patient's skin is
shown on which a selected dermatologic treatment is to be performed. As
indicated earlier, the treatment may be for removal of unwanted hair,
tattoos, port wine stains, spider veins or other vascular lesions, etc.
The patient's skin has an epidermal layer 12 and a dermal layer 14, with
a dermal-epidermal (D/E) junction or basal layer 16 therebetween. While
some dermatologic treatments may involve heating the epidermis 17, such
as for example skin resurfacing, most dermatologic treatments which
involve the use of optical radiation treat a condition located at a
selected volume (sometimes hereinafter referred to as the target volume
or target) within dermal layer 14. For example, when the dermatological
treatment is hair removal, it may be desired to heat and destroy the bulb
18 of a hair follicle 20. While epidermis 12 might for example be 0.01 cm
deep, bulb 18 might, for example, be 3.0 to 5.0 millimeters into the
skin. Utilizing the teachings of this invention, a plurality of hair
follicles 20 may be simultaneously heated and destroyed.

[0035] The apparatus of this invention includes an applicator 22 which may
be mechanically driven, but which, for purposes of the following
discussion, will be assumed to be hand operated (i.e., translated over
the skin surface by hand). Applicator 22 includes a head 24 in contact
with the patient's skin in the treatment area and a handle 26 which may
be grasped by an operator to move head 24 in for example direction 28
across the patient's skin while preferably maintaining contact between
head 24 and the patient's skin. Such contact should be under sufficient
pressure between the surface of the head and the skin surface so as to,
for preferred embodiments, assure good thermal and optical contact
therebetween. Such pressure can be achieved by pressing the head against
the skin, by using negative pressure to press the skin against the head
or some combination of the two.

[0036] For some embodiments of the invention, a source of optical
radiation 30 is connected to a light pipe 32, which for the embodiment of
FIG. 1 is shown as extending through handle 26, but may otherwise be
connected to head 24, to selectively provide optical radiation to the
head, radiation being applied through the head, in a manner to be
discussed later, to the patient's skin. Source 30 may be a coherent light
source such as a ruby, alexandrite, or other solid laser source, a
gaseous laser source, or a diode laser source, or may be an incoherent
light source such as a flashlamp, fluorescent lamp, halogen lamp, or
other suitable lamp. Depending on the desired treatment, the radiant
energy may be at a single wavelength, with incoherent light sources being
filtered to provide the desired wavelength, or over a selected band of
wavelengths. In the following discussion, when it is indicated that
radiation is being applied at a selected wavelength, this will mean
either a single wavelength or a wavelength band, as appropriate. Source
30 in accordance with preferred embodiments of this invention is also a
CW source which, for purposes of this invention shall be defined as
either a light source which is producing radiation continuously or a
pulsed source with a high repetition rate/frequency, and in particular
which has a delay between pulses which is less than the dwell time of the
head on a given segment. CW radiation is defined as radiation from either
such source.

[0037] While in FIG. 1 source 30 is shown as external to head 24, for some
embodiments of the invention which involve the use of a diode laser,
diode laser bar or other sufficiently compact radiation source, the
source may be located in head 24, with wires for controlling and
energizing the source being connected through handle 26 or otherwise to
the head. Controls 34 are also provided which receive certain information
from head 24 over lines 36, for example information relating to rate of
movement of head 24 over the patient's skin, or temperature of the
epidermis and which may send control signals to the head over lines 38 as
required. Lines 36 and 38 may be part of a cable which is also connected
to head 24 through handle 26 or may be otherwise connected to the head.
Controls 34 may also generate outputs to control the operation of source
30 and may receive information from the source. Controls 34 may also
control selected output devices 40, for example a buzzer, light, vibrator
or other feedback control to an operator or, depending on application,
may be of other types known in the art.

[0038] Before discussing specific embodiments for head 24 and the manner
in which the system of FIG. 1 may be utilized to treat various
dermatological conditions in accordance with such embodiments, it should
be appreciated that maintaining head 24 in good thermal and optical
contact with the surface of the patient's skin during treatment while
applying CW radiation from source 30, whether located external to head 24
as shown in FIG. 1 or within the head, offers a number of significant
advantages when performing various dermatological treatments. First, as
indicated earlier, for the same radiation source operating at comparable
energy levels, a CW source is almost always substantially less expensive
than a comparable pulsed source. Therefore, the ability to use a CW
source results in a significant reduction in system cost. Second, if head
24 is moved across the surface of the patient's skin at a substantially
uniform rate, the radiation applied to the patient's skin at each point
along the path of travel of head 24 is substantially the same, something
which, as indicated above, cannot easily be achieved with a pulsed
radiation source. The head being in good optical contact with the
patient's skin improves the efficiencies of energy transfer into the
skin, further reducing the size and cost of the required energy source.
Further, the head 24 being in good thermal contact with the patient's
skin permits the head to be used to heat the volume in the patient's
dermis at which treatment is to occur, for example the area of bulb 18
for a hair removal procedure, so as to reduce the amount of energy
required from the radiation source in order to perform the desired
procedure at this volume, thus further reducing the cost of such source.
Good thermal contact also permits the head to be utilized to cool the
patient's epidermis 12 before irradiation, during irradiation, and after
irradiation, to protect the epidermis from thermal damage. Applying
pressure to head 24 as it is moved across the surface of treatment area
10 also stretches the skin in the treatment area which can provide a
number of advantages, including reducing the physical distance between
the head and the target volume, reducing the coefficient of scattering in
the skin so that more of the applied radiation reaches the target volume
and, for hair removal, flattening the hair follicle so as to increase the
area of the follicle exposed to radiation. All of these effects reduce
the amount of radiation required from the source, thereby further
reducing the cost of the system. Various techniques are available for
measuring/detecting good thermal contact between a head and the patient's
skin including the temperature profile detecting technique of copending
application Ser. No. 60/077,726 filed Mar. 12, 1998, which application is
incorporated herein by reference. FIG. 2 illustrates one exemplary
embodiment for a hand piece 24A suitable for use in practicing the
teachings of this invention. In the discussion of this embodiment, and in
the embodiments to follow, the same reference numerals will be used for
common elements. Letter suffixes will be used for elements which are
substantially the same, but differ in some particulars. Thus, the letters
24A, 24B, etc. are used for the various embodiments of handpiece 24.

[0039] Handpiece 24A has three sections, an optical channel 50 which is
shown in FIG. 2 as a waveguide, a leading section 52 which passes over
treatment area 10 before waveguide 50 and a trailing section 54 which
passes over the treatment area after waveguide 50. Optical radiation is
applied to waveguide 50 through optical fibers 32 (or fiber bundle) or
other suitable optical transmission components or, as will be discussed
later, laser diodes or other suitable components may be in contact with
waveguide 50. Waveguide 50 may also be replaced with a lens or other
suitable focusing or non-focusing optical transmission component (a
waveguide, lens or other suitable focusing or non-focusing optical
transmission component sometimes being collectively referred to
hereinafter as an "optical channel"), which optical transmission
component receives radiation from the radiation source utilized through a
suitable optical transmission path. Other arrangements for getting
radiation to optical channel 50 can also be employed.

[0040] Sections 52 and 54 are each formed of a metal or other material
having good thermal conduction properties. Sections 52 and 54 may be
formed as a single block of a single material, with optical channel 50
being formed in the block, or, where sections 52 and 54 are to have
different temperature profiles, the sections may, as will be discussed
later, be two separate sections of the same or different materials
secured together with a layer of thermal insulation therebetween. In FIG.
2, a thermal component 56a, 56b, 56c is shown in contact with section 52,
waveguide 50, and section 54, respectively. For a preferred embodiment,
each of the thermal components 56 is a thermoelectric element such as a
Peltier effect device; however, other mechanisms for controlling
temperature known in the art, including flowing water, and flowing gas or
spray at a desired temperature may be utilized for thermal components 56.
In applications where sections 52 and 54 have the same temperature
profile, the same thermal component may be used to control the
temperature of both sections; however, particularly if thermoelectric
components are used, it is preferable that a number of these components
be utilized, distributed over sections 52 and 54 so as to achieve a
substantially uniform temperature distribution in these sections.

[0041]FIG. 3 shows a head 24B which is substantially the same as the head
24A shown in FIG. 2 except that, in addition to sections 52 and 54, head
24B also has a section 58, ahead of section 52, with a thermal insulation
layer 60 being provided between sections 52 and 58. Section 58 is also
formed of a metal or other material having good thermal conduction
characteristics and a thermal element 56d, for example one or more
thermoelectric or thermal resistance elements, is provided in thermal
contact with section 58. As will be discussed shortly, section 58 is
intended to have a different temperature profile than section 52.

[0042] For the embodiment of FIG. 2, section 52 may be utilized to either
pre-heat or pre-cool the patient's skin in the treatment area. For a head
24 moving at a velocity V in direction 28, V sometimes also being
referred to as the "scanning velocity", and for a length of section 52 in
the direction of movement 28 equal to L1, the time T1 during
which section 52 is over a segment of the patient's skin prior to
treatment, and thus the time of pre-heating

T 1 = L 1 V ##EQU00001##

or pre-cooling, is roughly directly proportional to L1 and inversely
proportional to V. Thus,

T z = z 2 4 α ##EQU00002##

Since the time it takes for a temperature wave to penetrate to a depth z
in the skin is, where α is the skin thermal-diffusion coefficient
(α≈1.5 10-3 cm2/s). Therefore if these two times
(T1 and TZ) are roughly equal, then:

z = 4 α L 1 V ##EQU00003##

and the desired thermal effect will reach a desired depth z during the
period that section 52 overlies the skin segment. Thus, L1 and V can
be selected so as to achieve the desired thermal effect at a desired
depth in the skin prior to irradiation. Since, as will be discussed
shortly, V is also a factor in determining the duration of irradiation
for achieving the desired therapeutic effect, L1 may be the prime
factor in determining the depth for the desired thermal effect. For
pre-heating, the depth z is the depth of the volume at which treatment is
desired. For example, referring to FIG. 1, z might be the depth of bulb
18 of a hair follicle where the treatment is hair removal. For
pre-cooling, it is generally desired to cool the entire epidermis 12 to
DE junction 16. It is generally undesirable to cool significantly below
the DE junction since this may interfere with treatment by having some
cooling effect on the treatment or target volume. Depending on the
function section 52 is to perform and the scanning rate V, L1 is
selected so as to achieve the desired thermal effect to the desired depth
z.

[0043]FIG. 3 differs from FIG. 2 in that there are two pre-temperature
modifying sections 52 and 58. With this arrangement, section 58 is
typically heated to pre-heat to the depth zc of the target volume.
Section 52 is cooled and is intended to subsequently cool the epidermis
to roughly DE junction 16. Since heating performed by section 58 is to a
greater depth than the cooling performed by section 52, L4 is shown
as being greater than L1 in FIG. 3. The combination of sections 52
and 58 permits the target to be heated and remain heated prior to
irradiation while the epidermis is protected against thermal damage by
being cooled prior to irradiation.

[0044] The temperature profile at the depth z is a function of the initial
temperature of the skin and of the temperature of the section 52, 58 for
head 24B. The length of the segment L1 and scanning velocity V are
also factors in determining the final temperature at depth z. An estimate
of skin temperature at depth z can be made using Thomson's equation as
follows:

where T0 is the initial temperature of the skin, T1 is the
initial temperature of the segment which is assumed for purposes of the
equation to be segment 52. For scanning velocities in the range of
approximately 0.05 to 10 cm/s, and length L of approximately 0.125 cm,
desired pre-heating to a temperature in the range of +40° C. to
+60° C. or pre-cooling of -30° C. to +20° C. can be
achieved. Typically, the epidermis would be cooled to the DE junction to
a temperature in the -5° C. to 0° C. range. Scanning
velocities up to 10 cm/s should be achievable with contact scanning, but
scanning velocities in excess of 10 cm/s may be more difficult to
achieve.

[0045] The embodiment of FIG. 3 complicates the determination of
appropriate parameters since scanning velocity V, which is the same for
all sections, must be selected so that pre-heating can be achieved to a
desired depth with an L4 of reasonable size, pre-cooling to the DE
junction can be achieved with an L1 of reasonable size, and the
desired therapeutic effect can be achieved, using the radiation source
with a given fluence and for a reasonably achievable value of L2.
This is somewhat complicated by the fact that in order to heat deep
layers of the skin (i.e., greater than 3 mm) the scanning velocity should
not exceed approximately 0.1 to 0.2 cm/s, while for heating of subsurface
layers of the skin (less than 1 mm) the scanning velocity can be up to 2
cm/s. This assumes an L4 of approximately 5 cm or less.

[0046] Radiation passing through waveguide or other optically transparent
component 50 is directed through the epidermis, which has preferably been
pre-cooled to the target, which may have been pre-heated, in order to
achieve the desired therapeutic effect. In determining the time during
which the target is irradiated, account must be taken of the fact that,
due to scattering in the patient's skin, the beam width at the target can
be greater than L2, the width of radiation at the skin surface, by a
value Δ. Value L2+Δ can be minimized by focusing of the
beam. Thus, the exposure time T2 of the target to CW radiation is
given as,

T 2 = L 2 + Δ V ##EQU00005##

The target has a thermal relaxation time which is generally a function of
its size and of its shape. It is generally desirable that the time
T2 be roughly equal to the thermal relaxation time of the target,
assuming destruction of the target is the desired therapeutic effect,
since this results in maximum heating of the target with minimal heating
of surrounding tissue. In applications such as hair removal, where it has
been found that some damage to a small layer of tissue surrounding the
follicle facilitates permanent, or at least more permanent, hair removal,
it may be desirable for the time T2 to be slightly greater than the
thermal relaxation time of the target. In any event, for a target having
a size or diameter d, the critical velocity at which dwell time on the
target is roughly equal to its thermal relaxation time is given by,

V c = g ( L 2 + Δ ) α d 2 ##EQU00006##

where g is shape factor (g=8, 16 and 24 for stratified, cylindrical and
spherical targets, respectively). Thus, where bulb 18 of a follicle is
the target, g would be approximately 24. Assuming a maximum scanning
velocity of 10 cm/s, and also assuming a depth z≈3 mm and
L2+Δ of about 3 mm, equation (6) suggests that the process
works best for stratified targets like fat layer with a thickness greater
than 190 μm, cylindrical targets like a blood vessel with a diameter
greater than 270 μm, and spherical targets like a hair bulb with a
diameter greater than 320 μm. However, since, as discussed earlier,
lower velocities would typically be employed in order to achieve
pre-heating and/or pre-cooling for section 52, 58, significantly larger
minimum target volumes are required for the various shapes in a practical
system. However, since Vc is only a guide, and times less than or
greater than thermal relaxation time of the target may be appropriate in
some treatments, treatable target sizes will also vary. Effective
pre-heating of the target may also reduce the required dwell time to
achieve a desired therapeutic effect.

[0047] Another concern when employing the teachings of this invention for
dermatologic treatment is that the temperature rise at the target be
sufficient to achieve the desired effect.

[0048] Where the treatment being performed is hair removal utilizing
techniques similar to those described in U.S. Pat. No. 5,735,844 issued
Apr. 7, 1998, it is necessary to heat the hair bulb to a temperature of
approximately 65° C. to 75° C. The maximum temperature of a
hair bulb undergoing irradiation is given by the following equation,

where, z is the depth of the bulb 18 in the skin T0 is the initial
temperature of the bulb before irradiation a is the size of the irradiate
zone inside the skin along the scanning direction at the depth z (as
previously indicated a=L2+Δ) c and p are the heat-capacity and
density of the bulb respectively k(λ) is the absorbing ability of
the hair bulb and shaft defined by a concentration and a type of melanin,
and depends on wavelength (is greater for dark hair and less for lighter
hair) ψ(z, λ) is the radiance inside the skin at the depth z,
caused by a light flux of unit power per length. It depends on both
scattering and absorption inside the skin P is the power per unit length
(i.e., equal to the total power applied to the skin surface per width of
the light beam in the direction perpendicular to the direction of
scanning. P is in units of W/cm. τ(d)=d2/gα is a period of
thermal relaxation, where d is a diameter of the bulb, g is as previously
indicated equal to 24 for a hair bulb, and α is the thermal
diffusion coefficient of the tissue around the bulb.

[0049] For the destruction of a hair bulb, λ is in a range of
600-1200 nm and is preferably in a range of 670-1100 nm. In this range,
k(λ) varies from 1-0.1 and decreases with increasing wavelength.
ψ(z, λ) in this range increases with wavelength because of the
weakening of the skin scattering properties and decreases with depth. At
a depth of 3-5 mm where a hair bulb in its anagen stage is typically
locate, this value, which is sometimes referred to as radiance
attenuation, is in the range of 0.1-0.5. This value may be significantly
increased where focusing techniques to be described later are used. With
focusing, the reflection coefficient of light from the skin can be
20%-70%. Further, reflection of light scattered from the skin back into
it by various means to be described increases the radiance in the zone of
the hair bulge or in a hair bulb 1.2-2.5 times. Thus, the devices of this
invention can allow ψ(z, λ) to be increased to 0.5-1.

[0050] From the above, it can be seen that, once the geometry of the
systems has been selected, the temperature at the bulb is directly
proportional to the applied power P and is

T m = 6 P d k ψ g α c ρ a + T 0
##EQU00008##

inversely proportional to the velocity V in a more complex way. FIG. 15
illustrates the dependence of maximum temperature at a hair bulb on
scanning velocity V for typical parameters. The curve of FIG. 15 is
calculated assuming a=0.3 cm, k=0.5, ψ=0.5, P=40 W/cm2, d=0.03
cm. From FIG. 15, it is seen that at low scanning velocities, Tm
does not depend on scanning velocity and is equal to

V m = g a α 3 d 2 ##EQU00009##

When the scanning velocity exceeds temperature Tm starts to
decrease.

[0051] When V is less than Vm, the average temperature of the hair
bulb does not change with changing velocity, but selectivity of thermal
damage decreases. Thus, by decreasing the velocity of scanning, it is
possible to increase the diameter of the zone of thermal damage around
the hair bulb. Maximum scanning velocity depends on the hair bulb
dimension and decreases as the size of the follicle increases.

[0052] FIG. 16 shows the dependence of Tm for a hair bulb on the
power per unit length P. For a treatment period of less than 1 second,
denaturization of protein structures is observed at temperature exceeding
65° C. From FIG. 16, it is seen that maximum temperature Tm
at a hair bulb is also a function of the power P per unit length. For a
treatment of less than 1 second, denaturization of protein structures is
observed to occur at temperatures exceeding 65° C. FIG. 16 also
illustrates that the power required to cause thermal damage in a hair
bulb is inversely proportional to the size of the hair bulb (i.e.,
thermal damage is caused at a lower power for a large bulb than for a
small bulb).

[0053] Thus, for hair removal, and regardless of the embodiment utilized,
the following parameters would apply:

[0054] 1. Wavelength: 600-1200 nm;

[0055] 2. average power per length unit: 5-150 W/cm;

[0056] 3. width of beam along direction of scanning: 0.05-5 mm;

[0057] 4. scanning velocity: 0.01-10 cm/s;

[0058] 5. temperature of cooling: -20° C.-+30° C.

[0059] For preferred embodiments, optically transparent section 50 is also
cooled by thermal element(s) 56b so as to prevent, or at least limit,
heating of epidermis 12 in the treatment area during irradiation. This
cooling effect is also a function of the scanning velocity and is
particularly critical where irradiation used is of a wavelength which
preferentially targets melanin, as is for example the case for certain
hair removal treatments. Since there is a high concentration of melanin
at DE junction 16, it is desirable that V be slow enough so as to permit
heat produced at the DE junction to be removed through the cooled
waveguide or other cooled optically transparent element 50. The maximum
scanning velocity at which the cooling effect becomes noticeable for a
given depth z is given by,

V max = 4 L 2 α z 2 ##EQU00010##

Where epidermis 12 to be cooled has a thickness of approximately 100
μm and the length L2 is approximately 1 mm, Vmax=6 cm/s.

[0060] Further, as indicated earlier, the pressure applied to the skin by
head 24 in general, and by the skin-contacting surface of element 50 in
particular, has a number of advantages, including improving the optical
transmission (i.e., reducing scattering) for radiation passing through
the skin. The head moving in the direction 28 over area 10 of the skin
also stretches the skin in the direction of scanning resulting in an
additional increase in skin transmission and thus the depth of
electromagnetic wave penetration into the skin. Further, when the target
is for example a hair follicle, the stretching of the skin turns the
follicle to cause the radiation to impinge on a larger portion of the
follicle and brings the follicle nearer to the skin surface.

[0061] Section 54 continues to cool the epidermis after irradiation to
further guard against potential thermal damage to the skin. Unlike
lengths L1, L2 and L4 which are fairly critical, the
length L3 is not critical. The purpose of this section is to assure
that the epidermis is not overheated and, if the prior sections are
effective in keeping the epidermis temperature down, section 54 may not
be required.

[0062] Since it is generally desirable to decrease the time element 50 is
over the target, it is generally desirable that L2 be kept small.
However, in order to achieve more rapid treatment, a significant beam
aperture is desirable. This suggests that the dimension of the beam
perpendicular to the direction of movement should be relatively large,
resulting in an aperture for the skin contacting surface of element 50
which has an astigmatic shape, which shape may also be asymmetric. FIG. 6
illustrates two such shapes, namely an oval 66 (FIG. 6A), and a series of
adjacent light pipes 76a, 76b as shown in FIG. 6b, the light pipes of
FIG. 6b being discussed in greater detail in conjunction with FIG. 4.
These shapes are just examples of astigmatic shapes for an optical
aperture, and many other astigmatic shapes are within the contemplation
of the invention.

[0063] Further, in order to deliver the radiation to a significant depth
(i.e., greater than 1 mm) efficiently, large diameter beams are generally
required to overcome the effect of scattering. With astigmatic beams of
the type shown in FIG. 6, it is therefore desirable that focusing of the
beam in a direction perpendicular to the direction of scanning be used.
One way of achieving this is through use of a cylindrical lens 70 such as
is shown in FIG. 9 which lens has a small radius of curvature (for
example less than 10 mm). However, such focusing can perhaps be better
achieved through use of a head 24C such as that shown in FIG. 4. This
head has a section 52 which functions in the same way as section 52 of
head 24A to pre-cool or pre-heat the area under treatment. Section 52 is
separated from a section 72 of the head by a layer of thermal insulation
material 74. Section 72 is also formed of a metal or other material
having good thermal conduction properties. Two rows of micro-optic
elements 76a and 76b are provided which extend through section 72 and are
angled so that their focuses are combined along a common line located at
the target depth. Microlenses may be included at the distal ends of
elements 76 to enhance focusing. This technique allows the beams to be
targeted into the skin at angles greater and can be achieved using
optical systems and more effectively compensates for the scattering of
radiation in the skin. Section 72 would be cooled, preferably by a number
of thermoelectrical elements 56b, so as to provide both pre-cooling of
the epidermis prior to irradiation, cooling of the epidermis during
irradiation, and post-cooling of the epidermis. Section 72 can thus
perform the cooling functions of sections 50, 52 and 54 of for example
the embodiment of FIG. 2. Thus, for this embodiment of the invention,
section 52 can be used as a pre-heater or can be eliminated.

[0064] FIG. 4 also illustrates some additional features. First, it shows
an optical channel 78 which can be connected to a suitable detector in
controls 34 for detecting the scan velocity of head 28. Other techniques
which will be discussed in conjunction with FIG. 10 may also be used for
performing this function. Detecting scan velocity permits controls 35 to
operate output 40 if the scan velocity is detected to be outside of
desired ranges so as to alert the operator so that the rate may be
increased or decreased as appropriate. For example, the output may be a
red or a green light on some portion of applicator 22 or a console
associated therewith, might be a voice, or buzzer or other audio alert to
the operator, might be a vibrator in the handle 26, or might be some
other appropriate warning to the operator. In the event the rate is
detected as being so slow (or even no movement at all) as to present a
potential danger of injury to the patient, controls 34 might also
deactivate source 30 so as to protect the patient.

[0065] One problem with radiation treatments is that a significant
percentage of the radiation applied to the skin is reflected back or
backscattered by the skin and lost. Various schemes have been proposed in
the past for retroreflecting such radiation back into the skin, including
for example putting some type of reflector in section 50. Sections 52 and
54 might also have a reflective coating on their skin contacting surfaces
to reflect such radiation back into the skin. Section 72 is particularly
useful for this purpose since the entire skin-contacting surface 80 of
this section may be formed of highly reflective material, or have a
highly reflective coating formed thereon. By redirecting most of the
radiation back into the skin, the intensity of radiation inside the skin
can be increased 1.2 to 2.5 times.

[0066] FIG. 5 shows a head 24D an embodiment of the invention which
differs from that shown in FIG. 4 only in that there is a recessed
channel 84 formed in skin-contacting surface 80 of section 72, and that
optical channels 76a and 76b terminate on opposite sides of channel 84,
with their focal point being at a point in the recess, for example at the
substantial center thereof. A hose 86 is connected at one end to the top
of channel 84 and at the other end to a source of negative pressure. As
head 24D moves in direction 28 across the patient's skin, folds of the
patient's skin are drawn into channel 84. The size of channel 84 is
selected such that the target is included in the fold of skin drawn into
channel 84 and is irradiated from both sides by radiation applied to
optical channels 76. For example, if head 24D is being used for hair
removal, channel 84 might be 1 to 6 millimeters wide and 1 to 6
millimeters deep, a size which would generally result in the fold having
only a single hair follicle in the plane shown in the figure, although
multiple hair follicles may be in the channel along its long dimension.
The configuration of FIG. 5 has several advantages. First, it reduces the
distance for radiation to reach the target and more effectively focuses
radiation on the target. Second, if the channel is formed of an optically
reflective material, the walls of channel 84 reflect substantially all of
the radiation leaving the skin back into the fold, providing for very
efficient irradiation.

[0067] While in FIG. 5 it is assumed that a line connected to a vacuum or
other source of negative pressure is utilized to draw a fold of skin into
channel 84, a bellows or other suitable mechanism could also be utilized
for drawing the skin into channel 84 or, as shown in FIG. 7, a head 24E
could be provided having a channel 84' formed in a body 72' of a thermal
conductive material, which channel is shaped so that a fold of skin 90
which includes the target 92 is forced into channel 84' as head 24E is
moved in direction 28 over the patient's skin. Successive folds of the
patient's skin would be pushed into channel 84' as the head moves so as
to provide substantially uniform irradiation of the skin in treatment
area 10. Except that a pre-heater section 52 is not included, the
embodiment of FIG. 7 would otherwise operate in substantially the same
way as in the embodiment of FIG. 5 and would afford substantially the
same advantages.

[0068]FIG. 8 shows a head 24F which differs from those previously
described in that it has four sets of optical channels 76, channel 76a,
76b, 76c, and 76d, which for this embodiment are merely light paths
through a transparent block or air, each of which is fed by a
corresponding flexible waveguides 32a-32d, respectively. All of the
optical channels 76 are angled so as to be substantially focused at
target depth 92. Body 72'' is curved to facilitate the placement of
channels 76 and also has a reflecting top surface 93. In addition to
components previously mentioned, FIG. 8 also includes a line 94 leading
from a thermocouple or other suitable temperature sensor mounted close to
surface 80 or in surface 80. Temperature sensor line 94 connects to
controls 34 and may be utilized to control epidermal temperatures or for
other suitable purposes.

[0069]FIG. 9 shows still another embodiment of the invention which, as
previously indicated, utilizes a cylindrical lens 70 having a transparent
window 96 against which is mounted a radiation source 98, which may for
example be a laser diode bar, a lamp with a reflector, or other radiation
source which is small enough to be mounted in the handpiece. A reflection
plate 100 is provided to perform the retroreflection function for back
scattering light. FIG. 9 also shows a kinematic motion sensor 102 which
may either supplement optical motion sensor 73 or may be used in lieu
thereof. Kinematic motion sensor 102 may for example be a wheel which
turns as cylindrical lens 70 is moved over the skin surface to provide a
signal to controls 34 indicative of scan velocity. Temperature control
element 56 is shown as being in contact with both lens 70 and reflection
plate 100 so as to cool both elements, thereby providing both pre-cooling
of the treatment area and cooling during irradiation. There is preferably
a second element 56 on the opposite side of cylinder 70 in contact with
plate 100 on the trailing side of the lens which is operative both to
further cool the lens and to cool reflection plate 100 and the portion
thereof trailing the lens to provide post-cooling. As indicated
previously, cylindrical lens 70, particularly if it has a relatively
small diameter, for example of less than 20 mm, is also operative to
focus the radiation at target 92 and partly compensate the scattering
effect of skin. Except as indicated above, the embodiment of FIG. 9
operates substantially the same as the prior embodiments to provide
scanned CW dermatologic treatment. It should also be noted that, while
FIG. 9 is the only embodiment showing the radiation source 98 located in
head 24 as opposed to the radiation being applied to the head from an
external source 30 through optical leads 32, an external source 30 or an
internal source 98 for the head is interchangeable for all embodiments,
so that any of the prior embodiments may have an internal radiation
source 98 in lieu of the arrangement shown, and the embodiment of FIG. 9
may have an external radiation source with optical leads 32 impinging on
transparent window 96. For an embodiment such as that shown in FIG. 8, a
separate laser diode bar or bars 98 might for example be provided for
each of the optical channels 76a-76d.

[0070] FIGS. 10A and 10B show still another handpiece 24H suitable for
practicing the teachings of the invention. This handpiece differs from
those previously shown in that rather than radiant energy being applied
directly to the optical waveguide, lens or other transparent component
through which radiant energy is applied to the patient's skin, optical
lines 32 terminate in a cavity 106 formed in a body 108 of copper or of
some other material having good thermal conduction properties. The walls
of chamber 106 are polished, coated or otherwise treated to have highly
reflective, and preferably totally reflective, surfaces. The advantage of
the configuration shown in FIG. 10 with chamber 106 is that radiant
energy enters cylindrical lens or astigmatic microobjective 70' at a
variety of angles which can be focused by the lens/microobjective to the
desired depth in the skin, the focusing action being more efficient when
the light enters the lens at a variety of angles than at a single angle.
Cylindrical lens 70' may be mounted in body 108 either rigidly, as for
the embodiment of FIG. 9, or may be mounted for rotation in the body.
Rotation of the lens facilitates movement of the head over the patient's
skin, but prevents the desired stretching of the skin. However, a
rotating lens is within the contemplation of the invention. Thermal
elements 56 cool body 102, resulting in both pre-heating, cooling and
post-cooling of the epidermis and also resulting in the cooling of
cylindrical lens 70' which cools the epidermis during irradiation. Body
108 a has reflective skin-contacting surfaces 80 to retroreflect back
scattering light from the patient's skin. FIG. 10 also illustrates
kinematic motion sensor 102 and a thermocouple or other suitable
temperature sensor 94. Except for the differences discussed above, the
embodiment of FIG. 10 functions substantially the same as the embodiments
previously discussed.

[0071] FIGS. 11a-11c illustrate still another embodiment 241 for the head.
With this embodiment, cylindrical lens 112, which for example is formed
of sapphire, is treated to normally have total internal reflection so
that light or other radiation entering the lens through optical line 32
is reflected through the lens and exits through optical lines 32'.
However, when lens 112 is in contact with the patient's skin as shown in
FIG. 11c, the total internal reflection at the skin-contacting surface is
broken due to the change of index of refraction at this surface so that
light energy is emitted from the lens into the patient's skin. The use of
the total internal reflection lens 112 of FIG. 11 is a safety feature
which assures that radiation is not applied to a patient or other person
unless handpiece 24 is in contact with a patient's skin in the area to be
treated. Except for this difference, the embodiment of FIG. 11 functions
in the manner described for previous embodiments and components such as a
housing for pre- and post-cooling, a chiller for the lens, motion
sensors, etc. of prior embodiments might also be used with this
embodiment.

[0072] While for the embodiments of the invention described so far
radiation energy is applied in parallel along the length of the head
during irradiation, FIGS. 12a and 12b illustrate embodiments of the
invention where light is rapidly scanned. In FIG. 12a, radiant energy
applied to the head over a line 32 impinges on a deflector 120 which is
oscillated at a rate such that the impinging radiation is scanned in the
direction indicated by arrows 122 at the rate previously indicated across
a cylindrical lens 70''. In FIG. 12b, the impinging radiation 32 is also
applied to an oscillating deflector 120 which scans the beam into optical
fibers 124. Each optical fiber terminates in a microlens 126 mounted in a
plate 128 of a highly thermal conductive material. Plate 128 also
preferably has a highly reflective skin-contacting surface 80. So long as
the scan rate of deflector 120 is high enough, the radiation outputted
from cylindrical lens 70'' or microlenses 126 is CW radiation as this
term has been previously defined, and this system operates substantially
the same as for previous embodiments. Again, for purposes of simplifying
the drawings, elements such as thermal elements 56, motion sensor 78 and
102, and temperature sensors 94, are not shown in FIGS. 12a and 12b.

[0073]FIG. 13 is included to illustrate that pre-heating of the treatment
area, while more easily facilitated with the CW embodiments heretofore
described, is not limited to such embodiments and may be utilized with a
standard pulsed head of a type used in some prior art systems. In FIG.
13, radiation, which may be pulsed radiation from a source 30, is applied
trough optical lead 32 to an optical waveguide 50 having thermal elements
56 in contact therewith. Waveguide 50, having a focusing skin-contacting
end 132, is mounted in a suitable housing, a portion 130 of which is
shown in the figure. Thermal elements 56, which are thermoelectric
elements, for the embodiment shown, but may be other type of cooling, may
be operated to heat waveguide 50 for a time interval sufficient to heat
the skin to the depth z of the target. Either the same or a different set
of thermoelectric elements 56 may then be operated to cool waveguide 56
for a duration sufficient to cool epidermis 12 to the DE junction 16, at
which time source 30 is energized to apply radiation through waveguide 50
to the target. Cooling of waveguide 50 continues during this period to
maintain the epidermis at a desired temperature during irradiation and
the cooling of waveguide 50 may be contained for some period of time
after irradiation terminates to further protect the patient's skin.
Further, while preheating has been shown and described above followed by
epidermal cooling, and for many applications this is clearly preferable,
it is also within the contemplation of the invention to do preheating
without subsequent cooling. Head designs such as those shown in FIGS. 2,
4, and 5 (either with or without portion 52, and generally without),
8-12, might also be used when operating in a pulsed mode. Operation with
these heads in a pulsed mode could be similar to operation in a CW mode
except that movement of the head would be stepped rather than continuous.

[0074] While a number of embodiments and variations thereon have been
described above, it is apparent that these embodiments are for purposes
of illustration only and that numerous other variations are possible
while practicing the teachings of this invention. For example, while in
the discussion above it has been assumed that head 24 is manually moved
over the treatment area, this is not a limitation on the invention and
various types of mechanical scanners could also be utilized, either alone
or in conjunction with manual control. Further, while optical and
kinematic movement measuring mechanisms have been shown, suitable
thermal, electronic and magnetic movement measure mechanisms could also
be used. Controls 34 would function to maintain the required scan
velocity for such scanner. Thus, while the invention has been
particularly shown and described above with reference to preferred
embodiments, the foregoing and other changes in form and detail may be
made therein by one skilled in the art without departing from the spirit
and scope of the invention which is to be defined only by the appended
claims.